1. Field of the Invention
The present invention relates to a substrate processing apparatus and a substrate processing method for processing a substrate. Examples of substrates to be processed include semiconductor wafers, substrates for liquid crystal displays, substrates for plasma displays, substrates for FEDs (field emission displays), substrates for optical disks, substrates for magnetic disks, substrates for magneto-optical disks, substrates for photomasks, ceramic substrates, substrates for solar cells, etc.
2. Description of Related Art
In a manufacturing process for a semiconductor device or a liquid crystal display device, etc., processing liquids having different temperatures may be supplied successively to a substrate while rotating the substrate by a spin chuck. For example, Japanese Patent Application Publication No. 2009-238862 discloses that after supplying SPM (sulfuric acid-hydrogen peroxide mixture) having high temperature to an upper surface of a rotating substrate, DIW (deionized water) having ordinary temperature is supplied to the upper surface of the substrate that is covered with the SPM to rinse off the SPM attached to the upper surface of the substrate.
When a high-temperature SPM or other high-temperature processing liquid is supplied to a substrate, the substrate itself becomes high in temperature. When in the state where the substrate is covered with the high-temperature processing liquid, the supplying of an ordinary temperature DIW or other low-temperature processing liquid is started, the temperature of the substrate decreases suddenly and rapidly at a liquid landing position of the low-temperature processing liquid and at positions in a vicinity of the liquid landing position (hereinafter referred to as a “liquid landing position vicinity region”). Stress that contracts the substrate thus arises in the liquid landing position vicinity region and the substrate deforms so as to be warped or undulated due to a temperature difference between the liquid landing position vicinity region and another region that is in a high-temperature state. Although when the low-temperature processing liquid spreads sufficiently across the substrate, the temperature differences between respective portions of the substrate decrease and such deformation is resolved, the state in which the substrate is deformed is sustained until then.
With a clamping type spin chuck, a plurality of chuck pins are pressed against a peripheral edge portion of a substrate. When the substrate deforms in the state where the plurality of chuck pins are pressed against the peripheral edge portion of the substrate, the pressing pressures applied to the substrate by the respective chuck pins change and the stability of substrate holding by the spin chuck may decrease. Also, with a vacuum type spin chuck, a lower surface of a substrate is suctioned onto an upper surface of a spin base (suction base). When the substrate deforms in the state where the lower surface of the substrate is suctioned onto the upper surface of the spin base, the closely contacting state of the lower surface of the substrate and the upper surface of the spin base changes and the stability of substrate holding by the spin chuck may decrease.
In the abovementioned publication, it is disclosed that the SPM having high temperature (for example, 150° C.) and DIW having ordinary temperature (for example, 25° C.) are supplied to the substrate. The supplying of the DIW as the low-temperature processing liquid may thus be started in a state where there is a temperature difference of not less than 100° C. between the substrate and the DIW. The present inventors have confirmed that the deformation of the substrate can occur not only when the temperature difference between the substrate and the low-temperature processing liquid is not less than 100° C. but can also occur when the temperature difference is less than 100° C. (for example, at 60° C.). The deformation of the substrate can thus occur not only when the high-temperature SPM and the ordinary-temperature DIW are supplied successively but can also occur when other processing liquids with temperature difference are supplied successively to the substrate.